Oral Diltiazem Dosing for Atrial Fibrillation
For atrial fibrillation rate control, the recommended oral diltiazem dosage is 120-360 mg daily in divided doses, with extended-release formulations available for once-daily dosing. 1
Dosing Guidelines
Initial Dosing
- Standard starting dose: 120 mg daily, divided into multiple doses
- Extended-release formulations: Can be given as a single daily dose
- Titration: Increase gradually based on heart rate response
Maintenance Dosing
- Typical maintenance range: 120-360 mg daily 1
- Extended-release formulations:
- Once-daily dosing (improves adherence)
- Provides more consistent plasma levels
Administration Considerations
Formulation Options
- Immediate-release: Divided doses (usually 3-4 times daily)
- Extended-release: Once-daily dosing
- When transitioning from IV to oral therapy:
- Median oral dose is approximately 300 mg/day 2
- Start oral therapy 4 hours before discontinuing IV infusion
Monitoring Parameters
- Heart rate: Goal is generally 60-80 bpm at rest and 90-115 bpm during moderate exercise 1
- Blood pressure: Monitor for hypotension
- Symptoms: Assess for improvement in AF-related symptoms
- ECG: Evaluate for heart block or bradycardia
Special Considerations
Efficacy
- Diltiazem is a Class I recommendation (Level of Evidence B) for rate control in AF 1
- Studies show that medium-dose diltiazem (240 mg/day) combined with digoxin provides effective rate control both at rest and during exercise 3
- Higher doses (≥0.13 mg/kg equivalent) achieve faster heart rate control than lower doses 4
Safety Concerns
- Major side effects: Hypotension, heart block, heart failure 1
- Contraindications:
- AV block greater than first degree (without pacemaker)
- Sick sinus syndrome (without pacemaker)
- Decompensated heart failure/severe LV dysfunction
- Wolff-Parkinson-White syndrome with AF/atrial flutter
- Hypotension
Drug Interactions
- Diltiazem is a substrate of CYP3A4 and a moderate CYP3A4 inhibitor
- Significant interactions with: apixaban, itraconazole, bosutinib, ceritinib, cilostazol, cyclosporine, everolimus, ibrutinib, idelalisib, ivabradine, lomitapide, olaparib, ranolazine, rifampin, simeprevir 1
Alternative Rate Control Options
If diltiazem is ineffective or contraindicated, consider:
- Beta-blockers (metoprolol, propranolol)
- Verapamil
- Digoxin (particularly in heart failure patients)
- Amiodarone (when other measures are unsuccessful)
Clinical Pearls
- Heart rate control is generally considered adequate when ventricular response is 60-80 bpm at rest and 90-115 bpm during moderate exercise 1
- Combination therapy with digoxin may enhance rate control and allow for lower diltiazem doses 3
- Medium-dose diltiazem (240 mg/day) with digoxin provides effective and safe rate control with fewer side effects than high-dose diltiazem alone 3
- Extended-release formulations improve adherence and provide more consistent plasma levels throughout the day
Remember that the primary goal of rate control is to improve symptoms and quality of life while preventing tachycardia-induced cardiomyopathy, rather than achieving a specific heart rate target.